Corrosion prevention method and composition



2,882,227 Patented Apr. 14, 1959 CORROSION PREVENTION METHOD AND COMPOSITION Ramon I. Lindberg, Gary, Ind., assignor to Sinclair Refininlg Company, New York, N.Y., a corporation of ame Application February 23, 1954 Serial No. 412,059

12 Claims. (Cl 2528.55)

My invention relates to the prevention of corrosion in oil wells. In particular, I have found that the combination of a sulfonate type corrosion inhibitor and a germicide effective against sulfate-reducing bacteria effectively provides improved protection against rusting or corroding of the metallic equipment in the well. The crude oil so produced also possesses favorable rust-inhibiting properties when transported through connecting pipelines to the refinery.

Some degree of corrosion takes place in the metallic equipment, particularly iron, steel and ferrous alloy equipment, of practically all oil wells, and in certain environments, corrosion may reach costly proportions. The casing, tubing, sucker rods and lead lines are particularly subject to corrosive effects. The sucker rods and sucker rod boxes operate under heavy load conditions and are especially susceptible to failure by corrosion fatigue. As a result of corrosion, costs may be greatly increased because of the necessity of pulling tubing and sucker rods for repair or replacement. Indirect costs in terms of production losses while shut down for repair or replacement of rods, tubing, or other equipment may also prove to be considerable.

The most effective method of corrosion control appears to reside in the use of chemical inhibitors. Such chemicals have a distinct advantage over other methods in that all parts of the well fluid system can be protected. Sulfonate type corrosion inhibitors, for example, ammonium mahogany petroleum sulfonate, are particularly widely used for this purpose. Often, however, in the use of the sulfonate type inhibitors in actual field practice, the effectiveness of the inhibitor is satisfactory for a period and then suddenly decreases and extensive corrosion damage occurs. Increasing the concentration of the inhibitor does not improve the anti-corrosive effect and the corrosive action can only be stopped by changing to a non-sulfonate type inhibitor.

I have found that the introduction of a combination of a sulfonate type corrosion inhibitor and a germicide effective against sulfate-reducing bacteria into oil well fluids, surprisingly provides improved protection against corrosive action on the metallic surfaces in contact with the well fluids compared to the use of the sulfonate type inhibitor or germicide alone. Moreover, the anti-corrosive action remains effective for very satisfactory periods of time. The sulfonate type inhibitor and germicide in combination cooperate to provide improved protection against corrosive action on metallic equipment in contact with well fluids. Synergistic action is obtained in that the combination provides improved protection over that which'would be expected from the independent effects of the sulfonate type inhibitor and germicide.

According to my invention, the combination of inhibi-' tor and germicide is added as a compatible composition, as a mixture, or separately, to the oil well fluids. The combination is added by conventional methods, usually by merely injecting the desired amount down the annulus between the production tubing and the casing, The resulting crude from the well, after separation of the brine by conventional methods, displays favorable cor- No Drawing.

rosion inhibiting properties when transported through connecting pipe lines to the refinery.

The compositions of my invention comprise a sulfonate type corrosion inhibitor and a compatible germicide effective against sulfate-reducing bacteria. Advantageously, the inhibitor is an oil-soluble type and the germicide is a hydrocarbon-soluble type. The compositions are easily compounded compatible mixtures which can be readily utilized for corrosion control.

By a 'sulfonate type inhibitor I mean those inhibitors depending on a sulfonate base content for corrosion inhibiting activity. Suitable inhibitors include, but are not limited to, for example, neutralized hydrocarbon-soluble or mahogany petroleum sulfonic acids such as alkali and alkaline earth metal and ammonium mahogany sulfonates, which are oil-soluble types; neutralized hydrocarbon-insoluble or green petroleum sulfonic acids such as the salts of hydrocarbon-insoluble petroleum sulfonic acids and at least one aliphatic amine having from 12 to 30 carbon atoms per molecule described in the pending application Serial No. 334,979, filed February 3, 1953, of Robert L. Lothringer, now abandoned; and oilsoluble ammonia neutralized sulfonated mixtures of polyalkylated benzeues, i.e., the bottoms produced in the manufacture of monododecyl benezene (Neolene) which comprise didodecyl benzene and other polyalkylated benzenes, as described in pending application Serial No. 218,709, filed March 31, 1951, of Thomas G. Wisherd, now US. Patent Number 2,671,757.

The germicides useful in my invention are those effective against bacteria known as the sulfate-reducing or anaerobic type. The germicides include but are not limited to the following types: halogens, phenols, heavy metal salts, acids, triphenylmethane dyes, amines and aldehydes. By a halogen type germicide I mean to include halogens such as iodine and organic halogen compounds such as organic chloramines, e.g. Chloramine-T, a commercial germicide in which the active ingredient is sodium para-toluene sulfonchloramide, and chloro-. benzenes, e.g., Cuniphen 2722, a commercial germicide in which the active ingredient is 2,2-methylenebis (4-chlorophenol). By a phenol type germicide I mean to include phenols such as ortho-cresol and thymol (1-methyl-3-hydroxy-4-isopropyl-benzene), and halogenated phenols such as chlorinated phenols, e.g. Dowicide 6, a commercial germicide in which the active ingredient is tetrachlorophenol and Nalco 21-8, a commercial germicide in which the active ingredient is trichlorophenate and sodium pentachlorophenate. By a heavy metal salt type germicide I mean to include heavy metal salts such as copper salts, e.g. Cuprose," a commercial germicide in which the active ingredient is copper citrate, and organic mercury compounds, e.g. mercurochrome. By an acid type germicide I mean to include acids such as boric acid and 2,4,5-trichlorophenoxy acetic acid. Ex-. amples of triphenylmethane dye type germicides include dyes such as malachite green. Examples of amine type germicides include amine type compounds such as Nalco X-234, a commercial germicide comprising 1-(2-hydroxyethyl)-1-benzyl-2-tridecyl imidazolinium nitrite in an alcohol co-solvent. It is non-phenolic and contains no heavy metals. Examples of aldehyde type germicides include formaldehye.

The combination of inhibitor and germicide is generally used in amounts of about 1 to 50 pints per 1,000 barrels of well fluid, i.e. crude oil and brine. The proportion of germicide to inhibitor used varies according to the amount of bacterial contamination in the well and with the activity of the germicide. Generally, av proportion of parts of germicide is satisfactory. For example, about 20 pints ofthe combination per 1,000 barrels of well fluid in a proportion of 1 part of inhibitor'to 5 parts of ger-' the metallic surfaces involved. However, it may not be practical to rely on such physical inspections since the damage is then already effective. Accordingly, metal test blanks may be used for insertion into the well fluid and removed and examined at periodic intervals. Direct measurement of the well fluid acidity is also possible or a measure of the iron content may be made since this is an indication of the metal lost through corrosion.

Although I do not intend to'limit my invention by an explanation of its theory of operation, it appears that the germicide acts primarily to prevent the deterioration 1 of the sulfonate type corrosion inhibitor, although synergistic coperation between the inhibitor and germicide is observed. Anaerobic or sulfate-reducing bacteria which are present in water such as river and cstuarial waters now have been found to be present in oil well fluids. Apparently the bacteria cause the decomposition of a sulfonate type inhibitor, resulting in the release of hydrogen sulfide. The hydrogen sulfide causes rapid corrosion of metallic equipment even in the absence of oxygen to produce iron sulfide. It is well known that such bacteria reduce sulfur compounds such as sulfates, thiosulfates, sulfites, sulfonates and possibly even elemental sulfur to hydrogen sulfide as part of their normal metabolic processes. Thus, it appears that as sulfonates are one source of food for these bacteria, the failure of sulfonate type inhibitors is apparently due to this bacterial activity. In the prevention of corrosion by the use of sulfonate type inhibitors, the protection by sulfonate molecules depends upon the formation of a molecular film of the polar sulfonate molecule upon the metal. The sulfate-reducing bacteria apparently multiply on the surface of the metal where they may be protected by surface irregularities, cracks in mill scale and later by the corrosion product of their own attack. The intimate contact of both bacteria and sulfonate at the steel surface provides food for the bacteria by destruction of the protective sulfonate film, whereupon corrosion of the metal can proceed. The corrosion immediately results in deposition of hydrogen on nearby cathodic areas which again favors bacterial growth by providing the means to reduce the sulfonate. The end product of the bacterial attack is hydrogen sulfide, which is a severe corrodant and serves to accelerate the attack upon the metal. This would appear to explain why contaminated oil wells would suffer more rapid attack. Treatment of the wells is generally batchwise and not long after treatment the sulfonate content of the well fluid would be too low to replenish the adsorbed protective film as it was destroyed. By preventing the bacterial attack upon the sulfonates, however, the effectiveness of the sulfonate type inhibitor is preserved. Dispersants may be added along with the inhibitor and germicide to help in insuring that the ingredients reach the bacteria which may be lodged under the rust on the metallic surfaces.

The effectiveness of the combination of a sulfonate type inhibitor and a germicide of my invention will be further illustrated by the following examples.

Example I Tests were made to evaluate the corrosion inhibiting efiect of sulfonate, type inhibitors and germicides and the combination of the two inafluid' composed of crude;

oil and a synthetic brine (4 percent sodium chloride in tap water), which is more corrosive than natural brine. The presence of sulfonate-reducing bacteria in the crude oil sample was determined by culturing the bacteria using standard bacteriological techniques.

The materials were tested as oil well corrosion inhibitors inthe 'Lembcke test, which is performed as follows: A piece of mild steel, such as SAE 1010, measuring 2%" x V2" x A" is polished to a visually uniform surface on all six sides on a belt grinder using an grit, Alundum belt. After weighing, this strip is attached to a glass rod by means of small rings formed by cutting ,4 circles off of Tygon tubing. Two rings of plastic are passed over the glass tubing, the steel is placed on these two rings and a third ring is passed over both the glass tubing and the steel. Care is taken so that at no time is the metal coupon touched by bare hands. All manipulation is done with clean rubber gloves or fresh adsorbent tissues. The other end of the glass tube is placed into, but not through, a cork stopper. The glass tubing is bent in such a manner that when it is placed into a square, narrow mouthed, quart bottle the piece of steel will be close to, but not touching, one flat face of the bottle.

The requisite amount of sulfonate type inhibitor or germicide or both are placed into a clean, empty, narrow mouthed, square quart bottle and the bottle is flushed with illuminating gas until all air is removed. Then, under anaerobic conditions crude oil, which has been collected from an oil well and stored without access to oxygen under slight hydrogen sulfide pressure, and brine are added to the bottle in any desired ratio. After fluid addition the cork, glass rod, and metal test coupon are inserted into the bottle. The cork is driven flush with the bottle top and a screw cap is then placed on the bottle and tightened.

The bottle is then placed in a machine which rotates it for a given length of time, usually three weeks, at room temperature which is 72 to 76 F. Rotation is such that the metal strip is alternately exposed to oil, brine and gas in the bottle. After exposure the bottle is opened, the contents are dumped and the coupon is recovered. After solvent degreasing the metal coupon is treated with dilute, inhibited sulfuric acid followed by scrubbing with soap and water to remove corrosion products. After cleaning the coupon is weighed and the loss due to corrosion is determined. It is this loss which is measured.

Tabulated below are the results of tests run according to the above procedure. The metal strip was exposed for 21 days at room temperature to a fluid composed of a 9 to 1 ratio of hydrogen sulfide-saturated West Kansas crude oil and synthetic brine (4 percent sodium chloride in tap water). The sulfonate type inhibitor used was a reaction product of hydrocarbon-insoluble petroleum sulfonic acids and Duomeen T (an amino propyl tallow amine, RNHCH --CH CH,NH,, where R is the tallow radical consisting of fatty acids 16 to 18 carbon atoms in length with saturated and unsaturated chains present). The sulfonate type inhibitor and germicide were used in the indicated concentrations. The weight loss due to corrosion is measured in milligrams.

Bultonate inhibitor,

Germiclde, p.p.m. p.p.m.

Hydrogen blistering. I Average of 3 results.-

Other evaluations were made using the Lembcke test. The strip was exposed for 21 days at room temperature using a 9 to 1 ratio of hydrogen sulfide saturated West Kansas crude oil and synthetic brine (4 percent sodium chloride). The sulfonate type inhibitor was that of Example I. The inhibitor and germicide were used in the indicated concentrations. The results are tabulated below.

Sultanate Weight loss, mg.

inhibitor, Germicide 1 Average of 3 results. 2 A triphenylmethane dye of the formula:

Cs s Me i C=CQH|=NMB MegNCoHr Cl The test results again show the improved effect of a combination of a germicide and sulfonate type corrosion inhibitor in reducing corrosion.

Example III Other evaluations were made using the Lembcke test. The sulfonate type inhibitor was that of Example I. 80 cc. of West Kansas crude oil and 720 cc. of a synthetic brine (4 percent sodium chloride in tap water) saturated with hydrogen sulfide were used as the fluid in contact with the metal coupon for 21 days. The results are tabulated below.

Sultanate Weight loss, mg. inhibitor, ppm.

Germicide, p.p.m.

The above results clearly show the increased elfectiveness of the combination of a germicide and a sulfonate type corrosion inhibitor over the use of either material alone.

Example IV Evaluations of inhibitors other than sulfonate type inhibitors with germicides were made using the Lembcke test. Inhibitor A was Kontol-IZO," a commercial in- 6 hibitor containing the imidazoline group as the active ingridient and inhibitor B was a commercial inhibitor believed to consist of the reaction product of a long chain carboxylic acid and an amino propyl tallow amine as the active ingredient. Thus, the'inhibito'rs do not contain a su'lfonate base. The results are tabulated below.

Weight 108}, mg.

Inhlbltonpipm. Germlclde,p.p.m.

Nalco 21-S The results show that no beneficial effect regarding corrosion inhibition was obtained with the use of non-sulfonate type corrosion inhibitors with a germicide.

I claim:

1. In the production of oil from wells wherein well fluid is withdrawn from an oil well in contact with metallic surfaces, the method of reducing the corrosive action on such metallic surfaces in contact with said well fluid which comprises introducing into the well fluid a hydrocarbon-insoluble petroleum sulfonic acid neutralized with an amino propyl tallow amine of the formula RNHCH -CH CH NH where R is a tallow radical consisting of fatty acids 16 to 18 carbon atoms in length, corrosion inhibitor and a germicide effective against sulfate-reducing bacteria selected from the group consisting of 1-(2-hydroxyethyl)-1-benzyl-2-tridecyl imidazolinium nitrite, tetrachlorophenol, orthocresol, boric acid, 1-methyl-3-hydroxy-4-isopropyl-benzene, a sodium para-toluene sulfonchloramide, iodine, copper citrate and malachite green; said inhibitor being employed in a proportion of about 1 part to about 0.1 to 10 parts of germicide.

2. The method of claim 1 wherein the boric acid.

3. The method of claim 1 wherein the tetrachlorophenol.

4. The method of claim 1 wherein the sodium para-toluene sulfonchloramide.

5. The method of claim 1 wherein the malachite green.

6. The method of claim 1 wherein the iodine.

7. Crude oil to which favorable rust inhibiting properties have been imparted by the addition of a hydrocarboninsoluble petroleum sulfonic acid neutralized with an aminopropyl tallow amine of the formula where R is the tallow radical consisting of fatty acids 16 to 18 carbon atoms in length, corrosion inhibitor and a germicide effective against sulfate-reducing bacteria selected from the group consisting of l-(2hydroxyethyl)- l-benzyI-Z-tridecyl imidazolinium nitrite, tetrachlorophenol, ortho-cresol, boric acid, l-methyl-3-hydroxy-4- isopropylbenzene, a sodium para-toluene sulfonchloramide, iodine, copper citrate and malachite green; said inhibitor being employed in a proportion of about 1 part to about 0.1 to 10 parts of germicide.

8. The crude oil of claim 7 wherein the germicide is boric acid.

9. The crude oil of claim 7 wherein the germicide is tetrachlorophenol.

10. The crude oil of claim 7 wherein the germicide is sodium para-toluene sulfonchloramide.

11. The crude oil of claim 7 wherein the germicide is malachite grene.

12. The crude oil of claim 7 wherein the germicide is iodine.

germicide is germicide is germicide is germicide is germicide is (References on following page) '7 8 References Cited in the file of this patent "2,632,694 a Watkins Mar. 24, 1953 I I STATES PATENTS v I T.-'-;. Mar. 9, 252 Menual Egg OTHER REFERENCES gggg %g$ i; a 1950 Shock et a1.: Prediction of Corrosion in Oil and Gas 2583399 Wachter gg; 1952 Wells, article in The Petroleum Engineer Reference An- Neg L 1952 nual 1951, pp. B86, B88, B90, B92, B94, B96 and B98.

2,629,693 Barton et a1 Feb. 24, 1953 

1. IN THE PRODUCTION OF OIL FROM WELLS WHEREIN WELL FLUID IS WITHDRAWN FROM AN OIL WELL IN CONTACT WITH METALLIC SURFACES, THE METHOD OF REDUCING THE CORROSIVE ACTION ON SUCH METALLIC SURFACES IN CONTACT WITH SAID WELL FLUID WHICH COMPRISES INTRODUCING INTO THE WELL FLUID A HYDROCARBON-INSOLUBLE PETROLEUM SULFONIC ACID NEUTRALIZED WITH AN AMINO PROPYL TALLOW AMINE OF THE FORMULA R-NH-CH2-CH2-CH2NH2, WHERE R IS A TALLOW RADICAL CONSISTING OF FATTY ACIDS 16 18 CARBON ATOMS IN LENGTH, CORROSION INHIBITOR AND A GERMICIDE EFFECTIVE AGAINST SULFATE-REDUCING BACTERIA SELECTED FROM THE GROUP CONSISTING OF 1-(2-HYDROXYETHYL)-1BENZYL-2-TRIDECYL IMIDAZOLINIUM NITRITE, TETRACHLOROPHENOL, ORTHOERESOL, BORIC ACID, 1-METHYL-3-HYDROXY-4-ISOPROPYL-BENZENE, A SODIUM PARA-TOLUENE SULFONCHLORAMIDE, IODINE, COPPER CITRATE AND MALACHITE GREEN; SAID INHIBITOR BEING EMPLOYED IN A PROPORTION OF ABOUT 1 PART TO ABOUT 0.1 TO 10 PARTS OF GERMICIDE. 